Positioning of the socket relative to the foot of a lower limb prosthesis is critical to comfort, function, and health of the residual limb and intact musculoskeletal system. Achieving proper alignment is currently a time-consuming and imprecise art that requires considerable skill and effort on the part of the prosthetist, and permits no direct control by the patient. The proposed project will significantly advance the alignment process. The objective of the proposed work is to refine a Robotic Prosthetic Alignment system (RoboPAL) that enables the alignment of lower limb prostheses to be rapidly adjusted by robotic control. A prototype system developed in Phase I successfully allowed both the prosthetist and the prosthesis user to specify alignment changes via a hand-held control unit communicating wirelessly with an actuator unit integrated with standard modular components. The technology permits the prosthetist to concentrate on "the big picture" (i.e. eliminate time on the floor with wrenches in hand), and will enable the patient to participate more fully by directly controlling adjustments. In addition, the system will be capable of accepting input from the Computerized Prosthetic Alignment System (ComPAS), a separate technology that measures loads transmitted through the prosthesis, calculates magnitude and direction of misalignment, and outputs direction and magnitude of advised alignment modifications. When RoboPAL and ComPAS are used together, the result is an auto-aligning limb. The system also opens the door for telemedicine applications adjustments directly controlled by experienced practitioners observing patients via web-streamed video in areas without adequate prosthetic care. In the proposed work, we will refine the successful Phase I design, then build and test the definitive RoboPAL system, and finally evaluate performance and functional outcomes with human subjects. PUBLIC HEALTH RELEVANCE. This project will advance the important process of aligning the components of lower limb prostheses. The technology will allow the prosthetist to adjust the alignment quickly, easily, and in a more well-controlled manner than is currently possible. It will also allow the prosthesis user to directly participate in aligning the limb, will be usable as part of an auto-aligning limb and will make it possible for alignment to be accomplished remotely through a telemedicine paradigm.